Airgap micro-spring interconnect with bonded underfill seal

Abstract

A package includes a pad chip having contact pads, a spring chip having micro-springs in contact with the contact pads to form interconnects, the area in which the micro-springs contact the contact pads forming an interconnect area, an assembly material between the pad chip and the spring chip arranged to form a gap between the pad chip and the spring chip, and an underfill material in a portion of the gap to form a mold from the pad chip and the spring chip. A package includes a pad chip having contact pads, a spring chip having micro-springs in contact with the contact pads to form interconnects, the area in which the micro-springs contact the contact pads forming an interconnect area, an assembly material between the pad chip and the spring chip arranged to form a gap between the pad chip and the spring chip, an underfill material in the gap to form a mold from the pad chip and the spring chip, and at least one wall between the underfill material and the interconnect area. A method of assembling a package includes aligning a pad chip with a spring chip to form at least one interconnect in an interconnect area, adhering the pad chip to the spring chip so that there is a gap between the pad chip and the spring chip, dispensing underfill material into the gap to seal the interconnect area from an environment external to the package, and curing the underfill material to form a solid mold.

1. A package, comprising:
 a pad chip having a surface with which contact pads are in contact; 
 a spring chip having micro-springs in contact with the contact pads to form interconnects, an area in which the micro-springs contact the contact pads forming an interconnect area; 
 an assembly material between the pad chip and the spring chip arranged to form a gap between the pad chip and the spring chip; 
 an underfill material in a portion of the gap away from the interconnect area to form a mold from the pad chip and the spring chip; and 
 a wall surrounding the interconnect area to separate the underfill from the interconnect area. 
 
     
     
       2. The package of  claim 1 , wherein the assembly material comprises one of a self-curing adhesive, a moisture-activated adhesive, a thermally-curable adhesive, solder, and a UV-curable adhesive. 
     
     
       3. The package of  claim 1 , wherein the underfill material comprises one of a self-curing sealant, a moisture-activated sealant, a thermally-activated sealant, chemically-activated material, and a UV-curable sealant. 
     
     
       4. The package of  claim 1 , wherein the wall comprises a material that is compliant to surface topology and adjustable to fill voids in the gap during package assembly. 
     
     
       5. The package of  claim 1 , wherein the wall comprises a polyimide wall. 
     
     
       6. The package of  claim 1 , wherein the wall comprises a plurality of walls scattered around the interconnect area. 
     
     
       7. The package of  claim 2 , further comprising spacer beads in the assembly material arranged to define dimensions of the gap. 
     
     
       8. The package of  claim 1 , wherein the assembly material comprises an adhesive into which spacer beads are mixed. 
     
     
       9. The package of  claim 1 , wherein the pad chip further comprises a substrate of one of quartz, ceramic, a flexible organic material, metal, or a semiconductor. 
     
     
       10. The package of  claim 1 , wherein at least one of the pad chip and the spring chip, contain electronic or photonic devices such as transistors, photodetectors, LEDs, or laser diodes. 
     
     
       11. The package of  claim 1 , wherein the spring chip further comprise a substrate of one of quartz, ceramic, a flexible organic material, and a semiconductor. 
     
     
       12. A package, comprising:
 a pad chip having contact pads; 
 a spring chip having micro-springs in contact with the contact pads to form interconnects, an area in which the micro-springs contact the contact pads forming an interconnect area; 
 an assembly material between the pad chip and the spring chip arranged to form a gap between the pad chip and the spring chip; 
 an underfill material in the gap to form a mold from the pad chip and the spring chip; and 
 at least one wall between the underfill material and the interconnect area, the wall surrounding the interconnect area with the underfill away from the interconnect area. 
 
     
     
       13. The package of  claim 12 , wherein the wall comprises a wall surrounding the interconnect area. 
     
     
       14. The package of  claim 12 , wherein the wall comprises a plurality of walls arranged around the interconnect area. 
     
     
       15. The package of  claim 12 , wherein the wall comprises a polyimide wall. 
     
     
       16. The package of  claim 12 , wherein the wall defines a width of the gap between the pad chip and the spring chip. 
     
     
       17. The package of  claim 12 , wherein the wall comprises a compliant material.